REGRESSION (r294160): Occasional infinite loops under updateLayersFor…

…InteractionRegions

https://bugs.webkit.org/show_bug.cgi?id=240610
<rdar://problem/93507791>

Reviewed by Wenson Hsieh.

* Source/WebCore/page/InteractionRegion.cpp:
(WebCore::regionForElement):
Avoid emitting empty rects for interaction regions, and avoid emitting the region
at all if this results in an empty set of rects.

* Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeInteractionRegionLayers.mm:
(WebKit::updateLayersForInteractionRegions):
Never re-use a layer with empty bounds; we should never get here, but I'd rather
re-create the layer if we do than corrupt the hash table.

Canonical link: https://commits.webkit.org/250729@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@294467 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/page/InteractionRegion.cpp

@@ -107,23 +107,26 @@ static std::optional<InteractionRegion> regionForElement(Element& element)
         return rect;
     });
 
-    if (rectsInContentCoordinates.isEmpty())
-        return std::nullopt;
-
     if (is<RenderBox>(*renderer)) {
         RoundedRect::Radii borderRadii = downcast<RenderBox>(*renderer).borderRadii();
         region.borderRadius = borderRadii.minimumRadius();
     }
 
-    region.rectsInContentCoordinates = rectsInContentCoordinates.map([&](auto rect) {
+    region.rectsInContentCoordinates = compactMap(rectsInContentCoordinates, [&](auto rect) -> std::optional<FloatRect> {
         auto contentsRect = rect;
 
         if (&frameView != &mainFrameView)
             contentsRect.intersect(frameClipRect);
 
+        if (contentsRect.isEmpty())
+            return std::nullopt;
+
         return contentsRect;
     });
-
+
+    if (region.rectsInContentCoordinates.isEmpty())
+        return std::nullopt;
+
     return region;
 }
 

Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeInteractionRegionLayers.mm

@@ -87,8 +87,12 @@ void updateLayersForInteractionRegions(CALayer *layer, const RemoteLayerTreeTran
 
     HashMap<IntRect, CALayer *> interactionRegionLayers;
     for (CALayer *sublayer in layer.sublayers) {
-        if (isInteractionRegionLayer(sublayer))
-            interactionRegionLayers.set(enclosingIntRect(sublayer.frame), sublayer);
+        if (!isInteractionRegionLayer(sublayer))
+            continue;
+        auto enclosingFrame = enclosingIntRect(sublayer.frame);
+        if (enclosingFrame.isEmpty())
+            continue;
+        interactionRegionLayers.set(enclosingFrame, sublayer);
     }
 
     bool applyBackgroundColorForDebugging = [[NSUserDefaults standardUserDefaults] boolForKey:@"WKInteractionRegionDebugFill"];